The basic purpose of electric generators is to provide electric power. This is done by converting motive power from a machine into electrical power. This power is then used in an external circuit. This form of electric power can be obtained from a number of sources, including internal combustion engines, steam turbines, water turbines, hand cranks, and wind turbines.

Power stations

Electric generators at power stations produce electricity for the electricity grid. The process was first developed in 1882 in New York City, when a steam engine driving a dynamo powered public lighting on Pearl Street. Many cities around the world quickly adopted the new technology. Soon, electric lights were in use in public buildings, businesses, and public transport. The earliest power plants were coal or water-powered, but modern power plants use wind, solar, and geothermal energy sources.

Homopolar generators

Homopolar electric generators use two different forms of magnetic flux. In the first form, magnetic flux flows through a coil made of iron. In the second form, magnetic flux flows through a coil made of a nonferrous metal.

Induction generators

Induction generators are electromagnetic devices that use the force of magnetism to convert mechanical energy into electrical energy. To excite these devices, they need a certain external torque. This 3500 watt generator torque must be greater than the synchronous speed of the generator. However, this amount of torque cannot be increased indefinitely, so the generator can’t generate indefinitely. Instead, it must be kept within a certain range to avoid overspeeding.

Electromotive force

The electromotive force (EMF) is the energy transferred from a source to a load. This force can be generated by various devices, including electrochemical cells, thermoelectric devices, photodiodes, and Van de Graaff generators. An emf can also be produced by the fluctuations of the earth’s magnetic field. This can induce currents in the electrical grid.

Field winding

The field winding on an electric generator controls the reactive component of the power output. The stator, the center of the generator, provides a path for the continuously varying magnetic flux. The core of the stator is composed of thin sheets of magnetic steel. Since steel is an electrical conductor, a solid sheet would tend to short circuit the voltage, but the lamination breaks up the conducting path along its length. This helps to reduce the power losses that would otherwise occur in the stator steel. Inside the stator lamination, slots are punched to maintain an even distribution of power. A large generator will usually contain one turn of stator coils.

Permanent magnets

Permanent magnets in electric generators are used to attract and repel charges. In order to generate electricity, these magnets must be strong enough to pull the alternating current. These magnets are made of rare earth materials. Rare earth magnets have a high coercive force, and are also very resistant to corrosion. They are used in electric generators, electric motors, and other devices.